root@beaglebone:/sys/class/gpio# pwd
/sys/class/gpio
root@beaglebone:/sys/class/gpio# ls
export  gpiochip0  gpiochip32  gpiochip64  gpiochip96  unexport
root@beaglebone:/sys/class/gpio# echo 66 > export
root@beaglebone:/sys/class/gpio# ls
export  gpio66  gpiochip0  gpiochip32  gpiochip64  gpiochip96  unexport
root@beaglebone:/sys/class/gpio# cd gpio66
root@beaglebone:/sys/class/gpio/gpio66# ls
active_low  direction  edge  power  subsystem  uevent  value
root@beaglebone:/sys/class/gpio/gpio66# cat direction
in
root@beaglebone:/sys/class/gpio/gpio66# echo out > direction
root@beaglebone:/sys/class/gpio/gpio66# cat direction
out
root@beaglebone:/sys/class/gpio/gpio66# cat value
0
root@beaglebone:/sys/class/gpio/gpio66# echo 1 > value
root@beaglebone:/sys/class/gpio/gpio66# cat value
1